Having multiple computers can be a blessing when trying to multi-task, but trying to control them all at once can take a lot of room. Hardware options are available. They are called KVMs, which is short for keyboard, video, and mouse switches. However these hardware options require a constant hardware connection. This makes it impractical for laptops, or when substituting the KVM for the real keyboard/mouse/screen set up is not desired.
This is where Synergy — a software option — can really shine. And yes, it works with Ubuntu. While Synergy is not a true KVM, it is quite helpful in a multiple computer situation. Synergy’s website probably says it best: